Healing of wounds (such as burn wounds, donor sites, incisional wounds, traumatic skin defects, decubitus skin ulcers, and diabetic skin ulcers) requires an environment that adequately keeps wound areas moist and that promotes cell growth. Thus, gauze, cotton wool, and the like have been used as wound dressings to be applied to affected areas. These dressings rapidly absorb exudate but unfortunately easily cause bacterial infection. Additionally, if the surface of wounds becomes dry, these dressings may cause pain or bleeding at the time of removal. A wound dressing may be used with an ointment or the like in order to prevent the surface of wounds from drying out. Yet, it results in insufficient absorption of exudate, and the surface of wounds may be kept too moist.
In addition, wound dressings such as carboxymethyl cellulose (CMC) gel (Patent Literature 1), which are intended to maintain a moist environment, may be used instead of gauze, cotton wool, ointments, and the like in order to maintain an adequate moist environment. Unfortunately, however, the CMC gel fails to sufficiently maintain the gel structure due to exudate and the like, and may be separated from the wound area or may create a hotbed for bacterial infection.
Meanwhile, a collagen sponge (Patent Literature 2) is known as a wound healing agent that not only maintains a moist environment but also promotes granulation tissue formation and epithelization. While the collagen sponges characteristically have good biocompatibility, they are unfortunately poor at maintaining a moist environment, easily cause bacterial infection and bacterial growth, and undergo degradation by exudate; and materials thereof are not easily available.
In addition, use of a conventional wound healing agent may cause a foreign body reaction (one of biophylactic reactions) which delays the transition to the inflammation phase in the course of wound healing process, resulting in delayed wound healing. Thus, there is a demand for a wound healing agent that minimizes foreign body associated with the wound healing agent.